The highest dose without dying? Pretty fucking high, I've taken 60 mg at once with no tolerance and had a sicknasty nod. But why would you want to waste your pills? I would recommend starting with snorting half the powder in one of the capsules, waiting 10 mins, seeing where you're at, snorting the other half. By that point you'll be floored

If you wanna pop em, start with a full 20 and then wait an hour and add another half a capsule - I wouldn't take two 20s at once with no tolerance, that's a waste, you really only need 15-20 mg oxy to get high af with no tolerance